installing Java : Java Glossary

The simplest way to install Java in order to run Java Applets, Java Web Start or
Java applications is just to click the Jump To
Java logo above and follow your nose. In just a few clicks, you
will be up and running. The rest of these instructions are to help you if something
goes wrong or if you are want to write your own Java programs.

To run Java programs, all you need is the JRE. If you want to write your own Java programs, you need the
larger JDK which includes the
JRE (Java Runtime Environment). You don’t need both.

You want the most recent version, Java
1.8.0_31. Last revised: 2008-01-16 Verified: 2008-02-09.
The Wassup Applet will tell you
if you already have it. If it fails to run, you don’t. You can also tell if you
have it already from the Java console.
Either offline or online
installation will work. The advantage of offline is you get a copy of the install to
keep to use for reinstall later. The advantage of the online install is it is a
little simpler. You don’t need both.

Unfortunately, there are still a four optional steps you must do manually after
you install Java:

Going into Control Panel ⇒ Java to tweak
options, e.g. to make the console
visible.

Repairing possibly
damaged Java Web Start Associations of the *.jnlp files
to be handled by javaws.exe in your browser. These tell
your browser to hand any *.jnlp Java Web Start files to
javaws.exe.

The associations for *.jar and *.jnlp are fragile. They mysteriously change to obsolete versions, or javaw.exe version without a console or even unrelated programs like Winzip.exe. Using the java.exe-jarmyjar.jar syntax in your bat/btm files rather is more robust than myjar.jar. It works even when the associations are
corrupted.